Radio communication devices include a transmitter and/or receiver coupled to an antenna which emits and/or detects radio frequency signals. The device may include a microphone for inputting audio signals to a transmitter or a speaker for outputting signals received by a receiver. Examples of such radio communication devices include one way radios, two way radios, radio telephones, personal communication devices, and a variety of other equipment. These communication devices typically have a standby configuration, wherein the device is collapsed for storage, and an active communication configuration, wherein the antennae is extended for optimum performance.
For radio telephones and two-way radios, it is typically desirable that these devices have a small size during a standby mode to facilitate storage and transport thereof. For example, users prefer that the radio telephones are small enough in the standby mode to permit storage in a shirt or jacket pocket. In the active communication state, it is desirable for the device to be sufficiently long to position the speaker adjacent to the user's ear, the microphone near the user's mouth, and the antenna away from the user's body. To meet these requirements, the radio telephone housing is reconfigurable to have smaller dimensions in the standby mode than they have in the active communication mode.
A difficulty encountered with prior art reconfigurable communication devices, such as radio telephones which must receive a call alerting signal in the standby mode, is providing a high performance antenna system in both the standby mode and the active communication mode. Although the extended antenna position allows for optimum antenna performance, the retracted position of the antenna in the standby mode which minimizes the dimensions of the communication device results in a decrease in antenna performance.
An example of a radio communication device including a multi-position antenna is a radio telephone including a body and flap, wherein the flap includes an antenna mounted thereon. When closed, the flap covers the radio telephone key pad and provides a compact housing. When the flap is opened, the flap antenna is spaced from the telephone body which the user holds. Although the flap antenna performs very well when the flap is open, the flap antenna is not ideally positioned to receive an alerting signal in the standby mode.
Accordingly, it is desirable to provide an antenna system having high performance characteristics when the communication device is extended in an active communication mode and when the communication device is collapsed in a standby mode of operation.